Lead scavenger compositions



United States LEAD SCAVEN GER COMPOSITIONS No Drawing. Application September 20, 1952, Serial No. 310,722

11 Claims. (Cl. 4469) This invention relates to compositions which are useful as scavengers with lead anti-knock compounds.

The use of lead compounds in gasolines to increase the octane ratings thereof is extremely widespread. There are, however, several rather serious adverse effects which accompany the use of leaded gasolines. One of these effects, the deposition of various lead compounds within the combustion chambers of the engines, has been at least partially remedied by the use of halohydrocarbon scavengers such as ethylene dibromide. Another adverse effect, which has been attributed to the lead anti-knock compounds, is mis-firing of the engine due to spark plug fouling. This spark plug fouling is quite prevalent under conditions of high temperature engine operation and, particularly in the case of aircraft engines, is a very serious type of trouble.

It is, therefore, an object of the present invention to overcome the previous shortcomings arising from the use of leaded gasolines. It is a further object to provide novel scavenger compositions for use with lead anti-knock compounds and in gasoline fuels. Another object is to provide novel fuel compositions containing said scavenger compositions. Other objects will be apparent hereinafter.

It has now been found that the use, as a lead scavenger in stable leaded gasoline fuel compositions, of a mixture of a halohydrocarbon scavenger and of a smaller amount of a hydrocarbyl-substituted-phenyl derivative of an oxide (including the sulfur and NH analogs) or hydride of arsenic, antimony or bismuth will result in greatly improved operation of spark ignition internal combustion engines. More particularly, the use of such scavenger compositions substantially eliminates spark plug fouling, or at least minimizes such fouling to a point where it is no longer a material consideration in engine operation. This outstanding advantage is obtained without having the other necessary characteristics (such as stability, performance rating, etc.) of the fuel deleteriously affected to any material degree by the presence of the scavenger compositions.

The arsenic, antimony and bismuth compounds of the present invention will be referred to hereinafter as antifouling compounds or anti-fouling agents. Arsenic, antimony, and bismuth are elements placed in group V-B of the periodic table as shown in Paulings General Chemistry (1948, Freeman & Co.).

The halohydrocarbon scavenger which makes up the major proportion of the scavenger compositions of the present invention may be, for example, any one or more of the numerous halogen scavenger compounds already known, such as ethylene dibromide and ethylene dichloride (U. S. 2,398,281), acetylene tetrabromide (U. S. 2,490,606), hexachloropropylene, monoand polyhalo propanes, butanes and pentanes (U. S. 2,479,900 and U. S. 2,479,902), polyhalo alkyl benzenes (U. S. 2,479,901 and U. S. 2,479,903), and the like, having a volatility between about 100 and about 0.1 mm. Hg at 50 C.

atent O "ice In general, the most effective anti-fouling agents of the present invention will be of the following formula:

wherein R is a hydrogen atom or an organic radical, but at least one of the Rs being a hydrocarbyl substituted phenyl radical,

Q is arsenic, antimony, or bismuth X is O, S, or NR x is an integer from 0 to 3, inclusive y is an integer from 0 to 1, inclusive z is an integer from 0 to 3, inclusive and x-i-z is not greater than 3 or less than 1.

It is preferred that all of the Rs in the foregoing formula be organic radicals, such as hydrocarbyl radicals. While non-hydrocarbon substituents do not generally adversely affect the efliciency of the compounds, it is preferred that the substituents be unsubstituted hydrocarbon radicals. The most effective compounds are those in which the R groups are all hydrocarbyl substituted phenyl groups. These hydrocarbon substituted phenyl groups may be alkaryl groups, fused ring polycyclic groups of the type of naphthyl or indanyl groups, or aryl substituted phenyl groups such as biphenylyl (or xenyl) groups. Alkaryl groups are preferred, especially poly alkyl substituted phenyl groups. The alkyl substituents should be lower alkyl groups of from 1 to about 12 or 15 carbon atoms, either branched or straight chain.

It is also preferred that x+z:3, and more preferred that x=3 and z=0. Of this latter type, the tri(alkaryl) tertiary arsines, stibines, and bismuthines are especially effective anti-fouling additives.

In general, the oxygen analogues of the anti-fouling compounds are preferable to the corresponding sulfur or imino analogues.

When using the scavenger compositions of the present invention, the total amount of halogen scavenger plus anti-fouling agent will generally fall between about 0.6 and about 1.5 theories, based upon the lead content of the gasoline, but may advantageously be as low as 0.4 or as high as 2.0 in some cases. The preferred range is from about 0.9 to about 1.2 theories.

The ratio of the two components of the scavenger composition is rather important. For example, if the proportion of halogen scavenger present is too large, excessive wear and corrosion of certain operating parts, such as exhaust valves and valve guides, is noted. If too small a quantity of halogen scavenger is used, the lead deposits are not efiectively scavenged. If too small a quantity of the anti-fouling compound is used, the spark plug fouling will not be materially reduced; and if too much of that compound is present the amounts of deposits and the plug fouling are both increased. In general, the theory ratio of the halogen scavenger or scavengers to the anti-fouling agents should be between about 3 :2 and about :1. For best results this ratio should be between about 2:1 and about 15: 1. As an additional limitation, the total scavenger mixture and the ratio of components therein should be adjusted so that the anti-fouling compound is present in an amount of between about 0.01 and about 0.6 theories, and preferably between about 0.05 and about 0.4 theories. A particularly desirable composition comprises 1 theory of the halogen scavenger and 0.1 theory of the anti-fouling compound. It is to be understood that more than one of the compounds from each class (i. e., halogen scavenger or anti-fouling agent), may be used in any single composition, just so the total quantity of each type falls within the limits set forth above.

The term theory, when used in conjunction with a halogen scavenger compound, designates the amount of scavenger required to react stoichiometrically with a given amount of lead anti-detonant so that all of the lead atoms and all of the halogen atoms form PbBrz or PbClz. In other words, a theory of scavenger is an amount which contains two atomic proportions of halogen for each atomic proportion of lead in the anti-detonant, or, a theory of the halohydrocarbon scavenger is one mol of the halohydrocarbon scavenger divided by one-half the number of halogen atoms per mol, for each gram atom of lead in the lead anti-detonant present, and therefore the number of theories of halohydrocarb'on scavenger present in a given composition is equal to the number of mols of halohydrocarbon present multiplied by one-half the number of halogen atoms per molecule, for each gram atom of lead in the lead anti-detonant present. As applied to the anti-fouling compounds, the term theory designates the amount required to react stoichiometrically with the lead so that all of the lead atoms and all of the arsenic, antimony, or bismuth atoms form Pbx(QO4)2, wherein Q is as defined above in (l), or, a theory of the arsenic, antimony or bismuth anti-fouling compound is one mol of such compound multiplied by two-thirds (that is, two-thirds of a mol of the arsenic, antimony or bismuth compound), for each gram atom of lead in the lead anti-detonant present, and therefore the number of theories of the anti-fouling compound present in a given composition is equal to the number of mols of the anti-fouling compound present multiplied by threehalves, for each gram atom of lead in the lead anti-detonant present.

While it is to be understood that the present compositions may be utilized in any leaded gasoline fuel, the compositions are of particular importance with respect to use in reciprocating internal combustion engine gasoline fuels, and especially such aviation fuels. This is true because of the relatively more frequent occurrence of spark plug fouling in aviation engines, with the greater inherent danger to human life in the case of failures of such engines. In addition to the lead anti-detonant and the scavenger composition, the gasoline fuels, or the concentrates for addition thereto may also contain corrosion inhibitors and stabilizers, such as 2,4-dimethyl-6-tertiarybutylphenol and other alkyl phenols, N,N-dibutyl p-phenylene diamine, hydroquinone, phenyl-alpha-naphthlyamine, N-butyl-p-aminophenol, alpha-naphthol, etc., dyes and the like.

By the term leaded gasoline, and the terms of similar import, is meant a petroleum fraction boiling in the gasoline hydrocarbon range (between about 50 F. and about 450 F.) to which has been added a small amount, usually between about 1 and about 6 cc. per gallon, of a metallo-organic, usually an organo-lead, anti-knock compound, such as a tetra-alkyl lead, e. g., tetra-ethyl lead, tetra-i-propyl lead, etc.

The fuels to which the present scavenger compositions are added are preferably those which are relatively stable with respect to oxidation or gum formation. The stability may result from the use of stable base stocks such as aviation alkylate, straight run gasoline fractions, or other fractions which have been highly refined to remove olefins, or the stability may result from the use of oxidation stabilizers, such as those mentioned above. The term stable gasoline as used herein refers to gasoline fuels having a maximum of mg. existent gum per 100 ml. of fuel (A. S. T. M. D.38l50), and a maximum of 10 mg. of gum per 100 ml. of gasoline after accelerated aging for 16 hours at 100 C. (The foregoing gum values apply to the fuel before addition of non-volatile additives, such as the anti-fouling agents of the present invention.)

As indicated above, the scavenger compositions of this invention are particularly useful in aviation gasoline. By the term aviation gasoline is meant a relatively high grade of gasoline fuel used in aviation engines, as distinguished from the lower quality gasolines, or motor fuels used in automotive engines. Aviation fuels have a more closely specified boiling range, generally running from a minimum of about 100 F. to a maximum of about 350 F. The anti-knock rating of such fuels is often appreciably higher than that of 100 octane number gasoline. Because of the demand for high quality, thermally cracked fractions are never used in aviation gaso lines. Catalytically cracked fractions may sometimes be used, but only after treatmentto remove olefins. One of the reasons for the restrictions upon incorporation of cracked gasolines in aviation fuels is that the oxidation stability of aviation fuels must be much greater than that required for motor fuels. For example, when tested according to a method such as described in the patent issued to Thomas W. Bartram, U. S. 2,256,187, an aviation fuel base stock will go well beyond 4 or 5 hours before the oxygen pressure will have decreased by 5 pounds per square inch.

The following are illustrative examples of compositions suitable for use according to the present invention:

Example I Tetra-ethyl lead 1.0 theory ethylene dibromide 0.2 theories tris-(2,5-dimethylphenyl) arsine Example II Tetra-ethyl lead 1.0 theory ethylene dibromide 0.1 theory tris-(2,5-dimethylphenyl) bismuthine Example III Tetra-ethyl lead 1.0 theory ethylene dibromide 0.1 theory p-octyl di-p-tolyl stibine oxide Example IV Tetra-ethyl lead 1.0 theory acetylene tetrabromide 0.4 theory 2-ethyl-4-t-butylphenyl dibenzenearsinate Example V octane aviation gasoline containing, per gallon:

0.5 cc. tetra-ethyl lead 1.0 theory ethylene dibromide 0.2 theory tris-(4-indanyl) stibine 0.02 gr. 2,4-dimethyl-6-tert.-butylphenol Example VI Aviation alkylate containing, per gallon:

4.6 cc. tetra-ethyl lead 1.0 theory ethylene dibromide 0.04 gr. 2,4-dimethyl-6-tert.-butylphenol 0.1 theory tri-o-cresyl arsenate Example VII Tetra-ethyl lead 1.2 theories hexachloropropylene 0.2 theory tris-(2,4,6-trimethylphenyl) bismuthine Example VIII Tetra-ethyl lead 0.8 theory ethylene dibromide 0.2 theory tris-(2,5-xylenyl) arsine sulfide Example IX Tetra-ethyl lead 1.5 theories hexachlorobutadiene-L3 0.1 theory tri(a-naphthyl) arsenite Example X 76 octane motor fuel containing, per gallon:

2.1 cc. tetra-ethyl lead 0.5 theory ethylene dichloride 1.0 theory ethylene dibromide 0.2 theory p-tolyl dichlorostibine 0.06 gr. N,N'-dibutyl p-phenylene diamine Example X1 115/ 145 grade aviation gasoline containing, per gallon:

4.6 cc. tetra-ethyl lead 1.0 theory ethylene dibromide 0.2 theory tris-o-tolyl bismuthine oxide 0.04 gr. 2,4-dimethyl-6-tert.-butylphenol Example XII Tetra-ethyl lead 0.5 theory ethylene dibromide 0.1 theory m-cresyl di-p-toluenearsinite Example XIII Tetra-ethyl lead 0.8 theory ethylene dichloride 0.2 theory tris-(o-tolyl) stibine sulfide Example XIV Tetra-ethyl lead 1.0 theory ethylene dibromide 0.1 theory 2,4,6-trimethylbenzenearsonous acid Example XV Motor gasoline containing, per gallon:

1.6 cc. tetra-ethyl lead 1.0 theory hexachloroethane 0.2 theory tris-(2,4-dimethyl-G-t-butylphenyl) arsine 0.06 gr. N-butyl-p-aminophenol Example XVI Tetra-ethyl lead 1.0 theory ethylene dibromide 0.05 theory di-(biphenyl) stibinic acid Example XVII Tetra-ethyl lead 1.0 theory ethylene dibromide 0.5 theory tris-p-cresyl arsine oxide Example XVIII Tetra-ethyl lead 0.8 theory ethylene dibromide 0.2 theory tris-(m-amino-p-tolyl) stibine Example XIX Tetra-ethyl lead 1.0 theory ethylene dichloride 0.1 theory di-(m-tolyl) 2,S-dimethylbenzenearsonate Example XX Tetra-ethyl lead 0.5 theory ethylene dichloride 1.0 theory ethylene dibromide 0.5 theory tris-(3,5-diethylphenyl) bismuthine Example XXI Tetra-ethyl lead 1.0 theory ethylene dibromide 0.1 theory diethyl 2,5-dirnethylphenyl stibme Example XXII Tetra-ethyl lead 1.0 theory ethylene dibromide 0.1 theory di-(3,5-xylyl) 3,5-xylenearsenne Example XXIII Tetra-ethyl lead 1.0 theory ethylene dibromide 0.1 theory tris-(2,4,6-trimethylphenyl) arsine 6 metallo-organic anti-knock agent, the halogen scavenger and the anti-fouling compound may be first mixed, stored and handled as a concentrate, and added to the gasoline at a later time. A typical concentrate of this latter type has approximately the following composition:

Weight percent Tetra-ethyl lead 55-60 Ethylene dibromide 25-30 Tricresyl arsine 10-15 Kerosene, inhibitor, dye stabilizer, etc. 3-6

Under other circumstances it may be desirable to mix the halogen scavenger and the anti-fouling agent, or the anti-knock agent and the anti-fouling agent, in the desired relative proportions and handle or store this mixture, with or without stabilizers, inhibitors, etc., as a concentrate for later incorporation with the other components of the ultimate fuel composition.

The present application is a continuation-in-part of our copending application Serial No. 242,309, filed August 17, 1951, which is in turn a continuation of our application Serial No. 167,376, filed June 10, 1950, now abandoned.

We claim as our invention:

1. A fuel composition for internal combustion engines consisting essentially of a stable gasoline, a minor efiective anti-detonant amount of an tetra lower alkyl-lead antidetonant, and a scavenger mixture for said anti-detonant consisting essentially of a halohydrocarbon scavenger and a compound selected from the group consisting of alkylsubstituted-phenyl derivatives of the hydrides, oxides and sulfides of an element of group VB of the periodic table having an atomic number from 33 to 83 inclusive, each phenyl group bearing from 1 to 3 of said alkyl substituents having from 1 to 15 carbon atoms each, said halohydrocarbon scavenger and said group VB compound being present in amounts such that, where (a) is the number of mols of said halohydrocarbon scavenger present multiplied by one-half the number of halogen atoms per molecule, for each gram atom of lead in the lead anti-detonant present, and (b) is the number of mols of said group VB compound present multiplied by threehalves, for each gram atom of lead in the lead anti-detonant present, the total of (a) plus (b) is from about 0.4 to about 2.0, (b) is from about 0.01 to about 0.6, and the ratio of (a) to (b) is from about 3:2 to about :1.

2. A gasoline fuel additive composition consisting essentially of an tetra lower alkyl-lead anti-detonant and a scavenger mixture for said anti-detonant consisting essentially of a halohydrocarbon scavenger and a compound selected from the group consisting of alkyl-substitutedaryl derivatives of the hydrides, oxides and sulfides of an element of group VB of the periodic table having an atomic number from 33 to 83 inclusive, each aryl group hearing from 1 to 3 of said alkyl substituents having from 1 to 15 carbon atoms each, said halohydrocarbon scavenger and said group VB compound being present in amounts such that, where (a) is the number of mols of said halohydrocarbon scavenger present multiplied by one-half the number of halogen atoms per molecule, for each gram atom of lead in the lead anti-detonant present, and (b) is the number of mols of said group VB compound present multiplied by three-halves, for each gram atom of lead in the lead anti-detonant present, the total of (a) plus (11) is from about 0.4 to about 2.0, (b) is from about 0.01 to about 0.6, and the ratio of (a) to (b) is from about 3:2 to about 100:1.

3. A lead scavenging composition for use with a leaded anti-detonant fuel for internal combustion engines, consisting essentially of a halohydrocarbon scavenger and of a compound selected from the group consisting of alkyl-substituted phenyl derivatives of the hydrides, oxides and sulfides of an element of group VB of the periodic table having an atomic number from 33 to 83 inclusive, each phenyl group hearing from 1 to 3 of said alkyl substituents having from 1 to 15 carbon atoms each, said halohydrocarbon scavenger and said group V-B compound being present in amounts such that where (a) is the number of mols of said halohydrocarbon scavenger present multiplied by one-half the number of halogen atoms per molecule, for each gram atom of lead in the lead anti-detonant present, and (b) is the number of mols of said group V-B compound present multiplied by three-halves for each gram atom of lead in the lead antidetonant present, the ratio of (a) to (b) is from about 3:2 to about 100:1.

4. A fuel composition for internal combustion engines consisting essentially of a stable gasoline, a minor effective anti-detonant amount of an tetra lower alkyl-lead anti-detonant, and a scavenger mixture for said anti-detonant consisting essentially of a halohydrocarbon scavenger and a alkyl-substituted aryl derivative of a hydride of an element of group V-B of the periodic table having an atomic number of from 33 to 83 inclusive, each aryl group bearing from 1 to 3 of said alkyl substituents having from 1 to 15 carbon atoms each, said halohydrocarbon scavenger and said group V-B compound being present in amounts such that, where (a) is the number of mols of said halohydrocarbon scavenger present multiplied by one-half the number of halogen atoms per molecule, for each gram atom of lead in the lead antidetonant present, and (b) is the number of mols of said group V-B compound present multiplied by three-halves, for each gram atom of lead in the lead anti-detonant present, the total of (a) plus (b) is from about 0.4 to about 2.0, (b) is from about 0.01 to about 0.6, and the ratio of (a) to (b) is from about 3 :2 to about 100:1.

5. A fuel composition for internal combustion engines consisting essentially of a stable gasoline, a minor effective anti-detonant amount of an tetra lower alkyl-lead anti-detonant, and a scavenger mixture for said antidetonant consisting essentially of a halohydrocarbon scavenger and a alkyl-substituted phenyl derivative of an oxide of an element of group V-B of the periodic table having an atomic number of from 33 to 83 inclusive, each phenyl group bearing from 1 to 3 of said alkyl substituents having from 1 to 15 carbon atoms each, said halohydrocarbon scavenger and said group V-B compound being present in amounts such that, where (a) is the number of mols of said halohydrocarbon scavenger present multiplied by one-half the number of halogen atoms per molecule, for each gram atom of lead in the lead anti-detonant present, and (b) is the number of mols of said group VB compound present multiplied by threehalves, for each gram atom of lead in the lead anti-detonant present, the total of (a) plus (b) is from about 0.4 to about 2.0, (b) is from about 0.01 to about 0.6, and and the ratio of (a) to (b) is from about 3:2 to about 100: 1.

6. A fuel composition for internal combustion engines consisting essentially of a stable gasoline, a minor effective anti-detonant amount of a tetra lower alkyl-lead antidetonant, and a scavenger mixture for said anti-detonant consisting essentially of a halohydrocarbon scavenger and an alkaryl arsine, each aryl radical hearing from 1 to 3 alkyl substituents and each alkyl substituent of which containing from 1 through 15 carbon atoms, said halohydrocarbon scavenger and said arsine being present in amounts such that, where (a) is the number of mols of said halohydrocarbon scavenger present multiplied by one-half the number of halogen atoms per molecule, for each gram atom of lead in the lead anti-detonant present, and (b) is the number of mols of said arsine present multiplied by three-halves, for each gram atom lead in the lead anti-detonant present, the total of (a) plus (b) is from about 0.4 to about 2.0, (b) is from about 0.05 to about 0.4, and the ratio of (a) to (b) is at least 3:2.

7. A fuel composition for internal combustion engines consisting essentially of a stable gasoline, a minor eflective anti-detonant amount of a tetra lower alkyl, lead anti-detonant, and a scavenger mixture for said anti-detonant consisting essentially of a halohydrocarbon scavenger and a trialkyl-substituted phenyl arsine, each alkyl substituent of which containing from 1 through 15 carbon atoms, said halohydrocarbon scavenger and said arsine being present in amounts such that, where (a) is the number of mols of'said halohydrocarbon scavenger present multiplied by one-half the number of halogen atoms per molecule, for each gram atom of lead in the lead anti-detonant present, and (b) is the number of mols of said arsine present multiplied by three-halves, for each gram atom of lead in the lead anti-detonant present, the total of (a) plus (b) is from about 0.4 to about 2.0, (b) is from about 0.05 to about 0.4, and the ratio of (a) to (b) is at least 3:2.

8. A fuel composition for internal combustion engines consisting essentially of a stable gasoline, a minor etfective anti-detonant amount of tetraethyl lead, and a scavenger mixture for said tetraethyl lead consisting essentially of a halohydrocarbon scavenger and an alkaryl arsenate each aryl radical of which bears between 1 and 3 alkyl substituents, each alkyl substituent of which containing from 1 through 15 carbon atoms, said halohydrocarbon scavenger and said arsenate being present in amounts such that, where (a) is the number of mols of halohydrocarbon present multiplied by one-half the number of halo gen atoms per molecule, for each mol of tetraethyl lead present, and (b) is the number of mols of said arsenate present multiplied bythre'e-halves, for each mol of tetraethyl lead present, the'total of (a) plus (b) is from about 0.4 to about 2.0, (b) is from about 0.05 to about 0.4 and the ratio of (a) to (b) is at least 3:2.

9. A fuel composition for internal combustion engines consisting essentially of a stable gasoline, from about 1 to about 6 cc. of tetraethyl lead per gallon of fuel, and a scavenger mixture for said tetraethyl lead consisting essentially of a halohydrocarbon scavenger and tris (2,5- dimethylphenyl) arsine, said halohydrocarbon scavenger being present in an amount such that the number of mols of halohydrocarbon scavenger multiplied by one-half the number of halogen atoms per molecule, for each mol of tetraethyl lead present, is about 1.0, and said tris (2,5- dimethylphenyl) arsine being present in an amount such that the number of mols of said arsine multiplied by threehalves, for each mol of tetraethyl lead present, is about 0.2.

10. A fuel composition for internal combustion engines consisting essentially of a stable aviation gasoline, from about 1 to about 6 cc. of tetraethyl lead per gallon of fuel, and a scavenger mixture for said tetraethyl lead consisting essentially of ethylene dibromide and tricresyl arsenate, said ethylene dibromide being present in an amount such that the number of mols of ethylene dibromide, for each mol of tetraethyl lead present, is about 1.0, and said tricresyl arsenate being present in an amount such that the number of mols of said arsenate multiplied by threehalves, for each mol of tetraethyl lead present, is about 0.1.

11. A fuel composition for internal combustion engines consisting essentially of a stabilized automotive gasoline, a minor effective anti-detonant amount of tetraethyl lead, and a scavenger mixture for said tetraethyl lead consisting essentially of ethylene dibromide, ethylene dichloride and an alkaryl arsenate each alkyl substituent of which containing 1 through 15 carbon atoms, said ethylene dibromide, ethylene dichoride and alkaryl arsenate being present in amounts such that where (a) is the total number of mols of said ethylene dibromide and ethylene dichloride present, for each mol of tetraethyl lead present, and (b) is the number of mols of saidalkaryl arsenate present multiplied by three-halves, for each mol of tetraethyl lead present, the total of (a) plus (b) is from about 0.4 to about 2.0, (b) is from about 0.01 to about 0.6, and the ratio of (a) to (b) is from about 3:2 to about :1.

(References on following page) 2,750,267 9 10 References Cited in the file of this patent 2,477,220 Volz July 26, 1949 UNITED STATES PATENTS 2,506,847 T0111 y 1950 OTHER REFERENCES 2,013,198 Blount Sept. 3, 1935 2 151 432 Lyons et 1 Man 21 1939 5 I l n Engh ry, PP-

March 1951. 

1. A FUEL COMPOSITION FOR INTERNAL COMBUSTION ENGINES CONSISTING ESSENTIALLY OF A STABLE GASOLINE, A MINOR EFFECTIVE ANTI-DETONANT AMOUNT OF AN TETRA LOWER ALKYL-LEAD ANTIDETONANT, AND A SCAVENGER MIXTURE FOR SAID ANTI-DETONANT CONSISTING ESSENTIALLY OF A HALOHYDROCARBON SCAVENGER AND A COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKYLSUBSTITUTED-PHENYL DERIVATIVES OF THE HYDRIDES, OXIDES AND SULFIDES OF AN ELEMENT OF GROUP V-B OF THE PERIODIC TABLE HAVING AN ATOMIC NUMBER FROM 33 TO 83 INCLUSIVE, EACH PHENYL GROUP BEARING FROM 1 TO 3 OF SAID ALKYL SUBSTITUENTS HAVING FROM 1 TO 15 CARBON ATOMS EACH, SAID HALOHYDROCARBON SCAVENGER AND SAID GROUP V-B COMPOUND BEING PRESENT IN AMOUNTS SUCH THAT, WHERE (A) IS THE NUMBER OF MOLS OF SAID HALOHYDROCARBON SCAVENGER PRESENT MULTIPLIED BY ONE-HALF THE NUMBER OF HALOGEN ATOMS PER MOLECULE, FOR EACH GRAM ATOM OF LEAD IN THE LEAD ANTI-DETONANT PRESENT, AND (B) IS THE NUMBER OF MOLS OF SAID GROUP V-B COMPOUND PRESENT MULTIPLIED BY THREEHALVES, FOR EACH GRAM ATOM OF THE LEAD IN THE LEAD ANTI-DETONANT PRESENT, THE TOTAL OF (A) PLUS (B) IS FROM ABOUT 0.4 TO ABOUT 2-0 (B) IS FROM ABOUT 0.01 TO ABOUT 0.6, AND THE RATIO OF (A) TO (B) IS FROM ABOUT 3:2 TO ABOUT 100:1. 